81945602 has 18 divisors (see below), whose sum is σ = 127064763. Its totient is φ = 39634992.

The previous prime is 81945601. The next prime is 81945649. The reversal of 81945602 is 20654918.

It can be written as a sum of positive squares in 5 ways, for example, as 80120401 + 1825201 = 8951^2 + 1351^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=6401.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81945601) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 473588 + ... + 473760.

Almost surely, 2^81945602 is an apocalyptic number.

81945602 is a deficient number, since it is larger than the sum of its proper divisors (45119161).

81945602 is an equidigital number, since it uses as much as digits as its factorization.

81945602 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 422 (or 212 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 35.

The square root of 81945602 is about 9052.3810127502. The cubic root of 81945602 is about 434.3520577707.

The spelling of 81945602 in words is "eighty-one million, nine hundred forty-five thousand, six hundred two".